The overall goals of the proposed project are to translate analytical techniques developed in the field of basic science spine biomechanics to clinical studies for better understanding of the effects of spinal manipulative therapy on low back pain The specific aims of the proposed project are: (1a) To develop an analytical tool for facet kinematics analysis using 3D CT/MRI models and to validate it with cadaveric specimens, (1b) To validate an analytical tool to measure facet gap space using cadaveric specimen-specific 3D CT/MRI models, (2) To develop a novel analytical tool to measure 3D dimensions of the neural foramen and canal and validate the accuracy of these measurements using human cadaver specimens, and (3) To integrate these new and other existing standalone analytical tools into one user-friendly software package, to be made freely available on the web to investigators of large, multi-site clinical imaging studies on spinal manipulative therapies and the research community overall. New analytical tools for facet kinematics using 3D CT/MRI models and facet-based coordinate systems will be developed. A new method for 3D foramen and spinal canal analysis will be developed using a CT/MR combined 3D model. State-of-the-art technologies, which have been developed for spine biomechanics, will also be adapted for clinical studies on spinal manipulation. The analyses will include: 3D spinal alignment, 3D kinematics of the spinal motion segment during flexion, extension, lateral bending and axial rotation. These analyses will be helpful to understand the relationship between spinal structure and function and changes in spinal structure and movement before and after spinal manipulation. The new techniques to be developed in the proposed project will be validated using cadaveric specimens, and data on the accuracy of individual techniques will be provided for rigorous studies on spinal manipulation. The baseline information will be used for power analyses to assess sample size for future study designs. The analytical methods to be developed and adapted for the studies on effects of spinal manipulation will be integrated in one software package so that even the investigators who are not familiar with mathematical analyses can use these analytical methods. The software package will be released to the public domain through a dedicated website. The outcomes from the proposed study are expected to be equally effective for evaluating other forms of complementary and alternative medicine (CAM) for other musculoskeletal disorders.